"Hot on the heals of Oracle's revamp of Solaris support, the licensing agreement for free downloads of Solaris 10 have changed. Here is the bit in question: "...Please remember, your right to use Solaris acquired as a download is limited to a trial of 90 days, unless you acquire a service contract for the downloaded Software". So far the OpenSolaris license has not changed, it's still CDDL."

Top-notch documentation - try finding that for Linux. Or Windows, although acceptable Windows docs are usually available. I'm not familiar enough with OS X docs to know how good they are, though.

Boot environments - hose your configuration? Just boot into an older BE, and it's just like it was before.

Sane memory management - this is primarily a knock on Linux, but... it doesn't allocate memory that doesn't exist, unlike Linux. (That's not to say it doesn't allocate over the actual system RAM, it will, but only up to RAM+swap. Linux will allocate more than RAM+swap.)

I have to agree with you on the documentation while at the same time disagreeing. There are many aspects of Solaris which are really well documented. There are other sections which are more 'application' or 'daemon' specific which are very poorly documented.

The core operating system is great for docs, the additional services sometimes leave something to be desired.